RawDump2.0 works fine for GC backups....just burn the iso.
If you download and happen to get a *.gcn, just rename the extension to .iso and burn it, as long as it is 1,459,978,240 bytes, so I'm led to believe.
I've done about 15 so far (both ripped myself and dl'd) and they all work fine on 4.7G discs burned @ 16x (using Benq1640 and 'Record' 16x DVD-R)